Quick Charging Solutions Ease Smartphone Charging

January 03, 2017

Consumers today are relying on their smartphones more than ever before. IHS estimates that 1.38 billion smartphones shipped worldwide in 2015, and the market is expected to grow in the years ahead at an annual rate in low single-digit percentages. While the numbers may not increase rapidly, they are still impressive, and represent the largest unit shipments of any consumer device, far outstripping familiar items such as PCs or TVs.

These smartphones are changing over time as well. Processing capabilities increase, screens get larger, memory capacities grow, all of which boosts the draw on the battery. And while battery capacities are escalating with each generation, demands on the battery are expanding more rapidly, including rising use of phones as video viewing devices and gaming platforms.

The traditional method of charging mobile phones has been via the Universal Serial Bus (USB), which is currently implemented in phones through two connectors: micro-USB and USB Type-C. USB is the dominant method for transmitting data within PCs, consumer electronics and mobile devices. The USB Implementers Forum (USB-IF), which controls USB technology, also developed a power component. USB 2.0 devices delivered 2.5 watts of power for charging, while more recent USB 3.0 devices delivered 4.5 watts.

In the early part of this decade, mobile device and mobile semiconductor vendors became increasingly dissatisfied with the power delivery provided by the methods developed by the USB-IF. And some of these companies began to unveil their own quick charging solutions, which reduced the time needed to replenish mobile device batteries, while most maintained compatibility with the main USB charging standard.

Qualcomm’s Quick Charge technology is one of the prominent high-voltage quick charging methods. Quick Charge devices, which have been available since 2012, transfer power over the USB interface using standard USB cables and connectors. The most significant development for Quick Charge technology was the release of Quick Charge 2.0 in 2013, which can charge up to 75% faster than conventional methods. This made high-power charging readily accessible to mobile devices such as phones and tablets. Additionally, Quick Charge 2.0 provided the option of using five, nine or 12 volts. In November 2016, Qualcomm introduced Quick Charge 4, which offers 20% faster charging along with 30 percent higher efficiency compared to the previous generation solution. Quick Charge 4 also integrates USB Type-C and USB Power Delivery (PD) support.

Quick Charge’s advantages in the market include a significant installed base of mobile devices and power adapters as well as ease-of-use. Phone vendors using Quick Charge include Samsung, LG, Google, Motorola, HTC, ASUS, ZTE, Xiaomi, and others. Quick Charge’s primary drawback, which it shares with its competitors, is that it is ultimately a proprietary charging method, one that depends on USB ports governed by the USB-IF.

MediaTek introduced its PumpExpress+ fast charging system in mid-2014. It offered four voltages: five, seven, nine or 12 volts. PumpExpress+ 2.0 expanded the voltages from five to 20 volts, with .5 volt steps. And Pump Express 3.0, announced in late May 2016, offers three to six volt charging in ten to 20 millivolt steps, and charges bi-directionally over USB Type C connectors. Like Quick Charge, PumpExpress offers quick charging and a variety of voltages, but it lags behind Quick Charge in the number of mobile devices and accessories using it.

OPPO’s VOOC Flash Charge quick charging system was introduced in March 2014. Utilizing a specialized microcontroller chip and charging power of five volts, OPPO claimed to provide quick phone charging, along with high efficiency and lower temperatures. This proprietary system has recently been upgraded with the announcement of Super VOOC in the first half of 2016. The company claims that Super VOOC will allow a 2500 milliamp per hour battery to be charged through a five volt connection in 15 minutes. It will be compatible with both micro-USB and USB Type-C connectors. Presumably Super VOOC will remain proprietary and centered on OPPO products. While VOOC has the potential to offer the quickest charging available on any device, its availability is currently limited to eight models of OPPO phone.

HTC and Motorola have their own branded charging standards as well: HTC’s Rapid Charger and Motorola’s Turbo Charge. However, both standards are fully compliant with Qualcomm’s Quick Charge technology, and the difference is strictly in branding. Samsung employs both Quick Charge and its own Adaptive Fast Charging (AFC) standard.

The need for greater charging capability for USB-enabled devices has been recognized by the USB-IF, which introduced the Power Delivery (PD) 2.0 standard as part of the USB 3.1 specification announced in August 2014.

The PD 2.0 standard is designed to accommodate up to 100 watts of power with USB Type-C cables and ports compliant with PD 2.0. This will significantly shorten charging times for portable devices. In addition, voltage, current and direction of the Type-C interface can be negotiated without changing cable direction, expanding both power delivery and convenience compared to previous generations of USB. The drawback of PD 2.0 is that it is relatively late to quick charging, adds some complexity to the charging process, and suffers somewhat from the USB-IF’s unsuccessful history in delivering previous generation quick charging standard PD 1.0. In addition, PD 2.0 makes fast charging more expensive than existing technologies by increasing overhead, via a more expensive connector, more silicon, and other components.

The one thing all these quick charging standards have in common is the use of USB cables and connectors. USB offers many advantages. It is the most common port on phones as well as other mobile devices, such as media tablets. It also is very familiar to consumers, who likely already have at least a few USB cables in their house or office. Additionally, USB is an extremely versatile interface, with the ability to transmit data as well as power over a single connector.

The ubiquity and popularity of USB is undeniable. The question is: What to do about all the divergent quick charging standards that use it? Currently, USB as a power delivery specification lies most directly in the hands of the USB-IF. That organization has the power to make the future usability of proprietary charging specifications through USB connectors and cables difficult.

However, these existing proprietary standards work well, and are used by many millions of consumers in hundreds of devices. Qualcomm’s Quick Charge technology alone is currently found in over 100 devices and almost 300 accessories available worldwide today. And if for some reason existing fast-charging technologies could no longer use USB, they could be in danger of disappearing from the market, as USB is increasingly the only port available in non-Apple phones and tablets.

Overall, the market would benefit from co-existence between the USB-IF and the various companies with proprietary quick charging technologies that operate over USB. Effectively, the co-existence is already happening, as evidenced by hundreds of devices already in the market. However, some type of formalized acknowledgement of this co-existence might benefit both sides.

The benefits to proprietary quick charging backers are fairly obvious. The USB specification has an installed base in the billions of mobile devices alone. An acknowledgement of this co-existence would ensure the future of these alternate technologies by ensuring their continued access to USB. Increased cooperation might also save millions of quick charge adapters from the landfill. And it would likely ensure backward compatibility, allowing consumers to continue to use their existing alternate quick charge devices. The potential drawbacks for proprietary quick charging backers depends on the extent of the interaction with the USB-IF. If the proprietary standard were to be absorbed or allowed into some other standard, there might be a loss of control of the proprietary standard. Given the dominance of USB, however, it is not clear that absorbing proprietary charging methods into another standard is even possible.

What are the benefits to the USB-IF of a closer relationship with existing alternate quick charging technologies? It would enhance the USB-IF’s relationship with mobile phone makers and mobile semiconductor vendors, both intimately involved with the largest single application for USB devices: mobile phones. In addition, a roadmap to a future quick charging standard with input from all parties might create a charging standard with more complete best practices and buy-in from all sides. This has the potential to create a single specification that would reduce confusion in the market, and ultimately make consumers’ lives easier.

The drawback to the USB-IF could be more limited device deployment for PD 2.0 just as it is gaining traction in the market.

What would increased cooperation look like between the USB-IF and the companies with alternate quick charge technologies? It would likely start with some alteration of the USB-IF’s USB 3.1 Type C specification. Currently, the specification states that PD 2.0 is the only charging technology that can be used with Type C connectors. In lieu of cooperation, proprietary standards could enlist proprietary connectors, but to do so would entail extensive marketing challenges.

The benefits of cooperation for all parties outweigh the drawbacks, as it would benefit the consumer who currently uses any one of the quick charge standards with a USB cable. And the convenience of the customer should be everyone’s ultimate goal.